Telephone-exchange system.



UNITED STATES PATENT OFFICE.

HENRY P. CLAUSEN, OF MOUNT VERNON, NEW YORK, ASSIGNOR, BY MESNE ASSIGN-MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEWYORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented June 19, 1917.

Application filed December 12, 1914. Serial Non 876,795.-

To all whom it may concern:

Be it known that I, HENRY P. CLAUSE-N, a citizen of the United States,residing at Mount Vernon, in the county of Westchester and State of NewYork, have invented certain new and useful Improvements inTelephone-Exchange Systems, of which the telephone systems, particularlyofthe me-;

tallic circuit and central energy types.

One of the objects of this invention is to provide an improved meanswhereby a oentral oiiice operator may efl'ect the automatic connectionof a busy signal to a calling subscribers line with a minimum amount oflabor and time. This may be accomplished by an electromagnetic meansassociated with a link circuit at the central oiiice, and under thecontrol of the operator.v

Another object is the provision of means whereby the application of abusy signal to a calling subscribers line is delayed until the lapse ofa predetermined time. This means may comprise quick and slow actingelectromagnetic devices, which devices conjointly control theapplication of the busy signal to a calling line.

A further object is to provide means making it possible for a callingsubscriber to maintain control of his line circuit in such a manner thathe may effect the disconnection of the busy signal from his line andrecall the operator without the removal by the operator of her answeringcord plug from the subscribers line jack. This may be accomplished byelectromagnetic-means associated with the operators link circuit andunder the control of the subscriber.

The accompanying drawing illustrates diagrammatically one of thearrangements by which this invention may be eflectuated.

The subscribers stations Aand B, here shown equipped with the usualtelephone apparatus well lmown in the art, are con: nected by means ofline wires 1, 2 to a line jack 3 at the central oflice. Included in theline circuit is a line relay 4, which in pullingup its armature whenenergized by the removal of the receiver from the switch hook at thesubstation, lights a line lamp 5. Associated with the line jack 3 is acutoff relay 6, which becomes energized when the operator inserts theanswering plug of her cord circuit into'the jack in response to a call.At the central oflice there is provided the customary apparatus forconnectlng two subscriberslines together, which apparatus in accordancewith well known practlce, comprises an answering and calling plug 7 and8, respectively; an operators set 19- which may be connected with thecord circuit-by means of a listening key 20, and a source of operatingbattery. Included 1n the sleeve strands of the cord circuit aresupervlsory lamps 9, 9, having one side connected to battery and theother going to ground through the coil of the cut-off relays 7 and 8 areinserted 6, when the cord plugs in the line jacks 3. Bridged across thetip and ring strands of the cord circuit are relays 10 and 11, which areenergized whenever plugs? and 8, respectively, are connected to the linejacks 3 and the receiver is removed from the switchhook' at thesubstation.

The-relays 10 and 11 control the operation of the supervisory lamps 9,9, and the relay 10, in addition, controls a circuit of a locking relay12. The relay 12 is of a type slow in responding and its operation willbe hereinafter fully described. A busy signal 13, which is hereconventionally represented, is adapted to be inductively connected to acalling subscribers line by the conjoint action of the relays 12 and14:, the latter of which is associated with the operators set andadapted to be energized over the tipstrand of the calling plug 8,

when the operator makes a busy test of a called line in the usualmanner, as will be hereinafter fully set forth. The relay '14 may becommon to the various cord circuits of'an operators position as hereillustrated, or if desired, an individual relay may be provided for eachcord'circuit.

.As shown in the drawing, a source of ringing current is adapted to beapplied to the called subscribers line in a manner well lmown in theart. In the-arrangement shown, provision is made for selective ringing,which maybe accomplished by the operator pushing any one of the fourringing keys 16 to a way-down position, causing contact 17 to be closed.The closure of contact 17 completes a circuit through the ringing relay18, which relay effects the application of ringing current to the calledsubscribers line until its energizing circuit is interrupted by theremoval of the receiver from the switch hook when the called partyanswers, which operation will be hereinafter described in detail. Inevent the operator inadvertently plugs in on a subscribers line alreadyin use, to prevent either the calling or the called subscriber fromreceiving the busy signal, a guard relay 21 is provided which isadapted, upon energization to open circuit the locking relay 12.

The operation of the system thus described is as follows: Suppose thatsubscriber A. wishes to call subscriber B. Upon the re moval of thereceiver from the switch hook at substation A the line relay 4 isenergized, which in pulling up its armature closes contact 22, thuscompleting a circuit for the line lamp 5. The operator upon seeing theline lamp lighted, inserts her answering plug 7 into the line jack 3,and at the same time connects her set to the cord circuit by actuatingthe listening key 20. A circuit is now completed through the cutoffrelay (5 over the following path: battery 25, supervisory lamp 9,conductor 26, contact 27, conductor 28, sleeve side of the plug and jack7 and 3, respectively,-coil of relay ('3, to ground. Simultaneously withthe energization of .relay 6, relay 10 is operated by the closure of thefollowing circuit: battery 29, right-hand winding of relay 10, conductor30, line wire 1, through the substation. and back over line wire 2,conductors 31, 32, left-hand winding of relay 10, to ground. Relay 10 inpulling up its armature opens its back contact 27, thereby extinguishingthe supervisory lamp 9, as not sufficient current will flow through theresistance 23 to light the lamp.

The operator upon ascertaining that the calling subscriber desiresconnection with substation B, tests the busy condition of that line bytouching the tip of her calling plug 8 to the sleeve of the line jack 3associated with said line, as is common practice in the operation ofmultiple switchboards. If the called line is in use, the sleeve of themultiple jacks associated-therewith will have battery connected theretoat the time the busy test is made, and the operator in touching the tipof her plug 8 to the sleeve of the jack of said line (assumingsubstation B is busy), establishes the following circuit: battery fromthe sleeve of the jack, tip strand of plug 8, contact 34, conductor 35,contact 86, conductor 37, winding of relay 14, conductor 38, through thetertiary winding of the induction coil 39 associated with the operatorsset to ground. By this operation, the customary busy tone will beinduced into the operators receiver which informs her of the busycondition of the tested line. It may be noted here that the relay 14may, or may not, have been sufficiently energized to have been actuatedupon the completion of the circuit just described, but it is preferredto have this relay of a type quick in responding. The operator, byholding the tip of her plug on the sleeve of the line jack of substationB for a period somewhat longer than is customary for her to do whenoriginally testing the condition of the called line, permits the closureof the circuit through the relay 14 sufficiently long to operate saidrelay and effect the operation of the slowly responding relay 12. Relaylet in operating, closes contact 46, thus establishing a circuit for therelay 12 which may be traced as follows: battery 59, front contact 33 ofrelay 10, conductor 10, contact 4-1, conductor 42, coil. of relay -12,conductor 43, contact 44:, conductor 45, contact 46, to ground. Upon theenergization of relay 12, it forms a looking circuit for itself over thefollowing path: battery 59, front contact 33, conductor l0, contact &1,conductor 42, winding of relay 12, contact 47, conductors e8, 28, sleeveside of the plug and jack 7 and 3, respectively, coil of relay 6, toground. The busy signal is now connected to the subscribers line over apath which may be traced as follows: battery 29, right-hand winding ofrelay 10, conductor 30, over the line circuit and back, conductor 31,contact 50, to ground. It will be apparent that by virtue of the relay12 establishing a locking circuit for itself upon energization. theoperator is free to withdraw the callingplug 8 from the jack of thetested line and at the same time disconnect her set from the cordcircuit, as the busy signal will be continued back upon the line of thecalling subscriber until the circuit through the relay 12 has beenruptured. This may be accomplished by the subscriber workinghis switchbook, which will effect the (leenergization of relay 10 and theconsequent deenergization of relay 12 by the opening of the contact Atthe same time, the operator will be given the disconnect signal bythe'lighting of the supervisory lamp over the following path: battery25, lamp 9, conductor 26, contact 27, conductor 28, sleeve side of theplug 7 and jack 3, coil of relay 6, to ground. If the subscriber wishesto initiate another call, or communicate with the operator, he mayattract her attention by working his switch hook, which in making andbreaking the circuit through the supervisory lamp 9 will cause the sameto flash, thereby gaining the notice of the operator.

It may be noted here, that in event the called line happened to be atrunk line running to a private branch exchange, and was busy whentested by the operator, due to the fact that the relay 12 is of a typeslow in responding, she would have had an opportunity of testing all ofthe trunk lines running to the given private branch exchange before thebusy signal would have been connected to the calling subscribers line.In event all of the trunks happened to be busy, the operator would thenhold the tip of her calling plug on the jack of the last trunk testedlong enough to permit the actuation of the relay 12 and thus connect thebusy signal to the subscribers line by means of the conjoint action ofthe relays 12 and 14.

,Assuming' that the substation B was not in use when wanted bysubscriber A, the operator, after testing the line and finding it free,would insert the calling plug 8 into line jack 3. Ringing currentmay'then be applied to the line B by the operator depressing any one ofthe four keys 16 to a way-down position, which act would complete thecircuit for the ringing relay 18 which may be traced as follows: battery55, contact 57, conductor 58, coil of relay 18, contact 17, to ground.Upon actuation, relay 18 forms a locking circuit for itself through theclosure of the following circuit: battery 55, contact 57, conductor 58,

winding of relay 18, contact 60, conductor 61, contact 62, to ground.Thus ringing current is now applied to the line of substation B over thefollowing path: generator source 16, conductor 63, coil of relay 64,conductor 65, front contact 67, out over the line and return, contact66, to ground. Upon the called party removing his receiver from theswitch hook, the relay 64 becomes energized, opening contact 62, therebyinterrupting the locking circuit of the relay 18, which in turn removesringing current from the line of substation B.

Simultaneously with the removal of the ringing current from the line,the relay 11 is energized over the following path: battery 70,right-hand winding of relay 11, conductor 56, ring strand of the plug 8,out over the line and returning by the tip strand, contact 34, conductor35, contact 36, conductor 37, coil of relay 14, conductor 38, to ground.It will be noted that to effect the closure of the circuit just traced,the operator must not restore her listening key until the called partyhas responded. In pulling up its armature, relay 11 through the closureof contact 57, maintains itself energized in a manner self-evident. Whensubscriber B replaces his receiver upon the switch hook, the operator isinformed of this act by the lighting of the supervisory lamp 9 over thefollowing circuit: battery 51, lamp 9, conductor 52, contact 53,conductor 54, sleeve side of the plug 8 and jack 3, winding of relay 6,to ground.

In case the operator. should inadvertently plug in on a line already inuse, the relay 21, upon energization would open-circuit the relay 12which controls the application of the busy tone to the subscribers line,by opening the contact 41. This feature prevents either the called orthe calling sub scriber from receiving the busy signal, which is anadvantage if the operator had attempted to call a given subscriber whowas in the act of initiating a call or hanging up his receiver at thecompletion of a call. It will be apparent that the application of thebusy tone to the subscribers line is under the control of both of therelays 12 or 21.

The fact that the calling subscriber maintains control of his line atall times through the means herein described, makes it feasible toemploy the use of a graphophone as a busy signal if desired. In eventthe graphophone was used in giving a busy signal and had been connectedto a subscribers line, if it proved displeasing to the subscriber, hemay rid himself of the annoyance by merely working his switch hook.

From the above it will be apparent that an operator can make a quickbusy test.

aving once completed the necessary steps to connect the busy signal to acalling subscribers line, in event the called line is in use, she mayrestore the calling plug to nor mal position and disconnect her set fromthe link circuit. The operator is thereby relieved of the necessity ofinforming the calling subscriber that the line called is in use, or ofconnecting her calling plug to a special busy jack. Her time is thussaved, thereby increasing her efiiciency. If the calling party wishesfurther service, or hangs up his receiver, the operator is immediatelynotified of that fact.

at is claimed is: v

1. A telephone system including telephone lines terminating in jacks ata central office, a link circuit at the central oflice for uniting linesin conversation, a busy signal, means made operative when said linkcircuit is contacted with a busy line to connect saidsignal to a callingline, means under the control of the calling subscriber fordisconnecting said signal from his line, and means for re establishingtelephonic connection with an operator without the necessity ofdisconnecting said link circuit from the jack of the calling line.

2. A telephone system including telephone lines terminating at a centraloflice, a link circuit at the central oflice for uniting lines inconversation, supervisory apparatus included in said link circuit, abusy signal, means made operative when said link circuit is contactedwith a busy line to connect said signal to the line of a callingsubscriber, and means controlled by the calling subscriber fordisconnecting said signal from the calling line and for maintaining saidsupervisory apparatus under control of the calling subscriber.

3. A telephone system comprising a calling and a called telephone lineterminating at a central office, a link circuit for connecting the linestogether, a supervisory signaling device in the link circuit, atone-producing device at the central office, means for connecting thetone-producing device in circuit relation with the calling line, meanscontrolled by the calling subscriber for disconnecting thetone-producing device from circuit relation with the calling line andfor causing the operation of the supervisory signaling device, and meansunder control of the calling subscriber for thereafter start ing theoperation of the supervisory signaling device.

4. A telephone system comprising telephone lin'es terminating at acentral office, a link circuit connected with one of the lines as acalling line, supervisory apparatus therefor, a quick and a slow-actingelectromagnetic device, energizing circuits therefor completed uponengagement of the link circuit with the terminal of a busy line, a busysignal connected with the calling line upon the energization of thedevices, and means controlled over the calling line for disconnectingthe busy signal therefrom and for maintaining the supervisory apparatusunder control of the calling subscriber.

5. In a telephone system, a calling and a called line terminating at acentral oliice, a link circuit for connecting the lines together, atone-producing device at the central oiiice, and switching mechanismcontrolled by and operated while the busy test is being made on thecalled line for con necting the tone-producing device in circuitrelation with the calling line at the expiration of a predeterminedperiod.

6. In a telephone system comprising a calling and a called telephoneline terminating at a central office, a link circuit for connecting thelines together, a tone producing device, means for connecting saiddevice in circuit relation with the calling line when said link circuitis contacted with the terminal of a busy called line, means under thecontrol of the calling subscriber for disconnecting said device fromcircuit relation therewith, and means for subsequently reestablishingtelephonic connection with an operator through said link circuit withoutthe necessity of disconnecting said link circuit from the calling line.

7. A telephone system comprising a calling and a called telephone lineterminating at a central office, a link circuit for connectin g thelines together, supervisory apparatus in the link circuit, atone-producing device, means for connecting the toneproducing device incircuit relation with the calling line when said link circuit iscontacted with the terminal of a busy called line, and means controlledby the calling subscriber for removing the tone-producing device fromcircuit relation therewith and thereafter maintaining the supervisoryapparatus under control of the calling subscriber.

8. In a telephone system, the combination of calling and calledtelephone lines, a main station at which said lines terminate, atelephone line connector at the main station pro-- vided with switchingmechanism to connect said connector to a called line, busy signalmechanism associated with said connector, means normally under the jointcontrol of said switching mechanism and the calling subscriber toconnect said signal mechanism in circuit with the calling line when saidswitching mechanism is contacted with the terminal of a line to whichanother connector is connected, apparatus automatically removing saidmeans from. the control of said switching mechanism when said busysignal mechanism is connected to said calling line, and devicescontrolled by the calling subscriber for disconnecting said signalmechanism from the calling line and restoring the control of said meansto the joint control of said switching mechanism and said callingsubscriber.

9. In a telephone system, the combination of a main station, a pluralityof substations one of which is a calling substation, a plurality oftelephone lines leading from the substations to the main stationincluding a calling telephone line to which the calling substation isconnected, a telephone line connector at the main station for connectingtelephone lines together adapted to be connected to said calling line,switching means for connecting said connector to a called line,controlled by said switching means for connecting said busy signalmechanism in circuit with the calling subscriber, said apparatus beingmade operative when said connector is contacted with a line to whichanother connector is connected, means for removing said apparatus :tromthe control of said switching means and placing such apparatus under thesole control of the calling subscriber, and means controlled by thecalling subscriber for causing the disconnection of said mechanism fromthe calling line and restoring it to the control of the switching means.

10. In a telephone system, the combination of a telephone line, atelephone line connector, busy signal mechanism associated therewith,means normally controlled by the connector and operative when theconnector is contacted with a line to which another connector isconnected for connecting said mechanism to the calling line, apparatusfor placing said means under the sole control of the calling subscriber,and means controlled by the calling subscriber r'or causing thedisconnection of said mechanism from the calling line and reassigningcontrol thereof to the connector.

11. In a telephone system, the combination of a main line, a pluralityof telephone busy signal mechanism and apparatus Cil lines leading tothe main station, one of which is a calling line upon which there is acalling subscribers substation, a connector at the main station forconnecting telephone lines together adapted to be connected to thecalling line, switching mechanism for connecting the connector to acalled line, busy signal mechanism associated with the connector,apparatus including a relay for connecting the busy signal mechanism tothe calling line, said apparatus being made operative when the switchingmechanism is contacted with a line to which another con nector isconnected, a locking circuit for said relay independent of the saidswitching mechanism, and means controlled by the calling line governingsaid locking circuit and adapted when the calling line is opened tointerrupt said locking circuit.

12. In a telephone system, the combination of a main station, aplurality of telephone lines leading from substations to said mainstation including a calling and a called line, connectors at the mainstation for con necting telephone lines together, busy signalingmechanism in said telephone system, apparatus for connecting saidmechanism in circuit with a calling subscriber when a connectorconnected to the calling line is contacted with the terminal of a lineconnected to another connector, means thereupon cooperating with theapparatus for removing the control thereof from the calling end of theconnector and means controlled by the calling subscriber fordisconnecting said mechanism from the calling line until said line isagain contacted with a busy called line.

13. In a telephone system, the combination of a main station, aplurality of telephone lines leading from substations to the mainstation, a telephone line connector at the main station adapted to beconnected to the calling line, means including a plug provided with atip contact for connecting the connector with the called line, busy signal mechanism in said system, an apparatus made operative when the tipof said plug 14. In a telephone system, the combination of a mainstation, a calling telephone line leading to the main station,substation apparatus on said line including an automatic receiver hookswitch, a called line leading to the main station, a cord circuit at themain station, an answering switch which when closed connects the cord tothe calling line, a second and calling switchfor connecting the cord tothe called line, said switch including switching terminals of the cordand switching terminals of the line, busy signal mechanism associatedwith the cord, apparatus for causing said mechanism to extend aprolonged busy signal to the calling subscriber, means under thejointcontrol of the calling subscriber and the operator during theestablishment of a connection and actuated when the call ing switchterminals of a cord and a called line to which another cord is connectedare contacted to cause said mechanism to extend the busy signal to thecalling subscriber, devices controlled by said means to place saidapparatus under the sole control of the subscriber, and mechanismoperating automatically when the calling subscribers hook switch isopened to restore said apparatus to the joint control of the callingsubscriber and operator.

In witness whereof, I hereunto subscribe my name this 10th day ofDecember A. D.,

- HENRY P. GLAUSEN.

Witnesses:

E. EDLER, K. L. STAHL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

